Re: Performance improvement for queries with IN clause - Mailing list pgsql-hackers

From Rafia Sabih
Subject Re: Performance improvement for queries with IN clause
Date
Msg-id CA+FpmFf1JtEXCB8j9uV2QFjN2utwgyFD2LnegHirtcmKw-YD-A@mail.gmail.com
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In response to Re: Performance improvement for queries with IN clause  (Andreas Karlsson <andreas@proxel.se>)
List pgsql-hackers
On Sat, 9 Nov 2019 at 12:52, Andreas Karlsson <andreas@proxel.se> wrote:
On 11/8/19 2:52 PM, Rafia Sabih wrote:
> Now, my question is shouldn't we always use this list in sorted order,
> in other words can there be scenarios where such a sorting will not
> help? I am talking about only the cases where the list consists of all
> constants and could fit in memory. Basically, when we are
> transforming the in expression and found that it consists of all
> constants, then sort it as well, codewise at transfromAExprIn, of course
> there might be better ways to accomplish this.
>
> So, your thoughts, opinions, suggestions are more than welcome.

If it is worth sorting them should depend on the index, e.g. for hash
indexes sorting would just be a waste of time.

Hi Andreas, 
Thanks for your response. Here, I meant this list sorting only for Btree, as you well pointed out that for other indexes like hash this wouldn't really make sense. 


--
Regards,
Rafia Sabih

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